Correlation between anti-mutated citrullinated vimentin and bone turnover markers (CTX-1 and P1NP) in patients with rheumatoid arthritis in remission and low-disease activity

Introduction: Rheumatoid arthritis is associated with bone loss and the risk of osteoporotic fracture. Bone loss in this disease is mediated by inflammation and autoimmunity. Many studies have shown that anti-citrullinated protein antibody is capable of inducing bone loss through several mechanisms. This study aimed to determine the relationship between autoimmunity, represented by anti-mutated citrullinated vimentin (anti-MCV) in this study, and bone loss, represented by C-terminal cross-linking telopeptide of type I collagen (CTX-1), and N-terminal pro-peptide of type 1 procollagen (P1NP) in this study, in patients with rheumatoid arthritis in remission and low disease activity. Material and methods: This study enrolled 38 rheumatoid arthritis patients with disease remission and low disease activity in Cipto Mangunkusumo Hospital between August and September 2019. We collected the patients' demographic data, Disease Activity Score 28 (DAS28), and treatment history. All participants underwent blood work for anti-MCV, CTX-1, and P1NP. Results: Thirty-four of the subjects were women (89.5%), with the mean age of 40 ±7.6 years and the median disease duration of 36 months. Among the subjects, 26 patients (68.4%) were anti-MCV positive. There was no correlation between anti-MCV and CTX-1 levels (r = 0.101, p = 0.274). There was a moderate negative correlation between anti-MCV and P1NP (r = -0.449, p = 0.001). The mean difference of P1NP according to anti-MCV level also showed a significant difference (p = 0.019) Conclusions: The anti-MCV levels are not directly correlated with CTX-1 levels, indicating heterogeneity in the disease course even after inflammation has ceased. The anti-MCV and P1NP levels are moderately correlated, indicating that bone formation is resumed during the suppression of autoimmunity.